Shimano BT-E8035 Integrated Battery Issue: very fast degrading and loss of range


jimbob

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My 2p on the situation, having been following the various threads for a while and trying to understand whats going on.

I will try to stick to facts, as that's what we need. There is a lot of speculation, but not much evidence / data to back it all up.

The feature ( I'll call it that, we don't know its an actual problem) only appears on the E8035.

What has been seen is the battery / system is reporting a degradation of the battery faster than expected. This degradation is consistent across most users, and occurs every 10 charge cycles. My own batteries have also followed this trend. There are some outliers to this, but have not seen any evidence of any batteries which significantly vary.

What we don't know (and I think was Gary's initial point) is if the capacity which is reported represents the actual battery capacity. I have seen no evidence to date which proves this.

There is lots of anecdotal data that the batteries are really degrading, but you could shoot holes through all of it unfortunately. The only way to be sure is run capacity tests on the batteries, which is hard to do.

I have been trying to do the next best thing by recording the power taken to charge the batteries up, by measuring the mains input power to the charger. Ill post some more details later, but this is still not a great test due to the number of variables, and will need to be plotted over a long period of time / charge cycles to have any hope of gaining meaningful data.
 

conman

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Jun 1, 2019
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Keswick
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Merida E-160 9000
I don't have any app to check the data on my 1 year old E8035 battery but I have noticed a significant drop in capacity. On one of my regular rides I used to get home with 2 full bars left now it's dropping to less than one. On another ride it used to drop into the final bar around 1 mile from home and now it drains completely before that.

Prevously I had a bike with a Bosch motor and battery for 2 years and hadn't really noticed any.
 

OleP

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Dec 3, 2020
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63
Roskilde, Denmark
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Gazelle Orange C8HMS
The feature ( I'll call it that, we don't know its an actual problem) only appears on the E8035.
No, it also happens with my BT-E6001 battery (E6100 motor and 'city bike'). 90 % health @ 10 full charges, 87 % @ 20 charges.
The bike is mostly used for recreational biking on paved roads and flat bike paths, so the battery is not heavely loaded.
Due to cold (freeze) weather and wind the range has gone down some 10 % in January and February, but seems to increase a bit again now.

I also measure and record the energy (Wh) when charging and calculates to Wh/full charge and although it is a rough measurement with many uncertainties, I do not see any significant change from September 2020 (when the bike was new) and until now (2000 km), even though the indicated battery health has gone from 100 to 87%.
 

Milan

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Sep 9, 2020
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eONEforty - Merida
My 2p on the situation, having been following the various threads for a while and trying to understand whats going on.

I will try to stick to facts, as that's what we need. There is a lot of speculation, but not much evidence / data to back it all up.

The feature ( I'll call it that, we don't know its an actual problem) only appears on the E8035.

What has been seen is the battery / system is reporting a degradation of the battery faster than expected. This degradation is consistent across most users, and occurs every 10 charge cycles. My own batteries have also followed this trend. There are some outliers to this, but have not seen any evidence of any batteries which significantly vary.

What we don't know (and I think was Gary's initial point) is if the capacity which is reported represents the actual battery capacity. I have seen no evidence to date which proves this.

There is lots of anecdotal data that the batteries are really degrading, but you could shoot holes through all of it unfortunately. The only way to be sure is run capacity tests on the batteries, which is hard to do.

I have been trying to do the next best thing by recording the power taken to charge the batteries up, by measuring the mains input power to the charger. Ill post some more details later, but this is still not a great test due to the number of variables, and will need to be plotted over a long period of time / charge cycles to have any hope of gaining meaningful data.
Still waiting for Shimano to warranty my battery. If they do not, I would have to prove the loss of capacity. In that case I will have to contact an expert to conduct such an analysis. What are the obstacles? Why is it hard to perform one?
 

jimbob

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Aug 3, 2020
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Cannondale Motera 5
Still waiting for Shimano to warranty my battery. If they do not, I would have to prove the loss of capacity. In that case I will have to contact an expert to conduct such an analysis. What are the obstacles? Why is it hard to perform one?
The main issue is that you cannot discharge the battery out of the bike.

In simple terms, to determine the battery capacity you need to discharge it over a fixed load (resistor for example) whilst measuring the voltage across it and current flowing through. From this, you are able to work out the power which the battery can provide.

The batteries (e8035 anyway, but that's all I have) have electronic switches inside. These are 'turned on' by the rest of the system when in the bike. You would need to reverse engineer this protocol and then reigate it to be able to conduct such a test. It wouldn't be hard, but adds a layer of complexity to the task. To me, this is the biggest hurdle.

If I get time, it's something I may have a go at doing, but have no plans to at the moment. It would be an interesting little project though.

For now, I'll continue to do the charging tests. This should do the same thing, as far as showing if the batteries really are degrading or not. But it won't tell you what the capacity is, if that makes sense. Only a relative number.

(side note) The available capacity will be dependant on the discharge rate, the lower the current, the higher the capacity will appear. This is typically done for 20hrs, which won't be realistic to our use. You would need to know the test which shimano use to get a measure relative to the specification, but if you did the test on your battery when new, it would show you a relative capacity which is still useful.
 
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jimbob

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Still waiting for Shimano to warranty my battery. If they do not, I would have to prove the loss of capacity. In that case I will have to contact an expert to conduct such an analysis. What are the obstacles? Why is it hard to perform one?
Forgot to add, for the warranty claim my first step would be taking to a shimano service center and getting them to run the diagnostics. Its the official shimano advice. If that indicates the battery has degraded more than they allow (80% at 500cycles or 60% at 1000), I would suggest they should replace.

It doesn't matter if the issue is with the reporting or the battery, you have evidence from a shimano rep that the battery falls within warranty criteria. I think it would then be difficult for them to argue against.
 
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Spiff

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Feb 27, 2019
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ebike
Forgot to add, for the warranty claim my first step would be taking to a shimano service center and getting them to run the diagnostics. Its the official shimano advice. If that indicates the battery has degraded more than they allow (80% at 500cycles or 60% at 1000), I would suggest they should replace.
Where did you get the Shimano statement about warranty replacement of the battery at 80% 500 cycles?
 

jimbob

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Where did you get the Shimano statement about warranty replacement of the battery at 80% 500 cycles?
It was on a shimano website somewhere. From memory its not under the warranty section, but under FAQs where they state the battery is good for 80% at 500 cycles and 60% at 1000.

I've just had a quick Google and can't find it again, but think I took a screenshot at the time in case they decided to remove it. I think there was a difference between UK and US website where the US only stated 60% at 1000.

ETA: nothing saying they would conduct a warranty replacement at those stages, but as they state thats how their product should perform, I would argue the product is defective if it doesn't meet those standards and so should be warranted, if that makes sense? Subtle but distinct difference!

It also correlates to a few on here who have now been asked to wait until the battery hits 80% indicated remaining capacity.
 

RickBullotta

E*POWAH Elite World Champion
Jun 5, 2019
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Just to be clear, this is a very REAL issue. Not just the 8035's. 8010's also. The useful battery capacity/life degrades FAR faster than Shimano's claimed 60% left after 1000 cycles. As you approach 70%, contact Shimano or a Shimano service center and start a warranty claim. This isn't just a "bad calculation" as some have suggested. Real world range is definitely affected as well, at least on my 8010's.
 
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RickBullotta

E*POWAH Elite World Champion
Jun 5, 2019
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Gary, you behave like a fourth grader. If you have nothing to add besides your sarcasm and think this post is stupid, just go and have sex with someone and don't spend your time here.

Use the "ignore" or "block" button on this forum - I did. I have no time for insecure, childish a$$holes.
 
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AusE

Member
Dec 3, 2019
54
68
Australia
So I had to take my merida 9000 to the shop for another reason other than the battery, whilst there they asked if it was going ok so I mentioned a drop in range. Shop mechanic connected to the computer showing 33 charge cycles with a capacity of 82%. Let's send it back he said, yesterday I received a message new battery is here. So obviously something is going on that they know about or I just got lucky.
 

Milan

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So I had to take my merida 9000 to the shop for another reason other than the battery, whilst there they asked if it was going ok so I mentioned a drop in range. Shop mechanic connected to the computer showing 33 charge cycles with a capacity of 82%. Let's send it back he said, yesterday I received a message new battery is here. So obviously something is going on that they know about or I just got lucky.
I guess you got lucky but it depends for how long... You will know right away, when you make your first 10 cycles. Unless, you are receiving a new battery with a new design, it will have the same fast degrading profile.
 

AusE

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Dec 3, 2019
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I guess you got lucky but it depends for how long... You will know right away, when you make your first 10 cycles. Unless, you are receiving a new battery with a new design, it will have the same fast degrading profile.
Yeah I guess I'll have to see how it goes, fingers crossed
 

guika

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Oct 31, 2020
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As I wrote it in the previous thread I do have the same issue.

10 cycles 90% it was around 600km
20 cycles 87% it was around 980km

Batt is 8035 ;) engine e8000
Slow charger
Storing always on 60-70% charge up before ride.

I charged the first 10 cycle inside the bike the 2nd 10 cycle outside the bike with shimano adapter.

Local shimano dealer said when i received 90% that i should wait for 20th cycle for replecament.

I will contact them on Monday and let see how its going.

I do have 1.0.0.0 fw inside the battery. Will see the new one.

I believe that BMS has something to do with it as battery mentioned in this and previous threads can not degrade in that exact way 10% the first ten and 3% on the second ten cycle...

I am heavy 115kg i am using the full spectrum based on my condition sometimes a lot of eco and rare trail. There are days when I go crazy and using boost 90% on my ride.

Feeling wise I do not really recognize that anything is really changed out of my distance what i do. I do have a friend who has an inbuilt ~380wah battery and he is around 80kg and his bike has the same age and almost same odo. When we ride together from the beginning and even today we loose the bars during riding almost the same time. We use almost the same modes when we ride together.Basically the weight differs which is explaining the situation.

I dont really lost km again feeling wise.

Keep you guys posted about the things and the replacent. I still believe that something is related to the BMS and it is a kind of bug.

One more info : Shimano said that it is not possible to upgrade the fw for the battery.
 
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Milan

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As I wrote it in the previous thread I do have the same issue.

10 cycles 90% it was around 600km
20 cycles 87% it was around 980km

Batt is 8035 ;) engine e8000
Slow charger
Storing always on 60-70% charge up before ride.

I charged the first 10 cycle inside the bike the 2nd 10 cycle outside the bike with shimano adapter.

Local shimano dealer said when i received 90% that i should wait for 20th cycle for replecament.

I will contact them on Monday and let see how its going.

I do have 1.0.0.0 fw inside the battery. Will see the new one.

I believe that BMS has something to do with it as battery mentioned in this and previous threads can not degrade in that exact way 10% the first ten and 3% on the second ten cycle...

I am heavy 115kg i am using the full spectrum based on my condition sometimes a lot of eco and rare trail. There are days when I go crazy and using boost 90% on my ride.

Feeling wise I do not really recognize that anything is really changed out of my distance what i do. I do have a friend who has an inbuilt ~380wah battery and he is around 80kg and his bike has the same age and almost same odo. When we ride together from the beginning and even today we loose the bars during riding almost the same time. We use almost the same modes when we ride together.Basically the weight differs which is explaining the situation.

I dont really lost km again feeling wise.

Keep you guys posted about the things and the replacent. I still believe that something is related to the BMS and it is a kind of bug.

One more info : Shimano said that it is not possible to upgrade the fw for the battery.
Some guys here will not like it, but, IMHO, you kgs do not matter, this battery has a got a certain profile to degrade fast and you will only realize that when you loose your km range and it becomes to be visible when the health of the battery is below or close to 80%. Most of the seasonal users (they hardly make 1k-1.5k per year) loose their warranty while not riding so frequent. They will not ever know they have been mistreated.
 
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guika

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Some guys here will not like it, but, IMHO, you kgs do not matter, this battery has a got a certain profile to degrade fast and you will only realize that when you loose your km range and it becomes to be visible when the health of the battery is below or close to 80%. Most of the seasonal users (they hardly make 1k-1.5k per year) loose their warranty while not riding so frequent. They will not ever know they have been mistreated.
Thats all good. I am sure as i wrote something is related to the BMS and please dont get me wrong I am not saying that it is not degrading. I just said feeling point of view not much I recognize.

i tried to make some measurement on that but it is hard in order not woid the warranty.

Never the less it is more than suspicious that 3-4 different riders different usage different kg different charger makes the same output on the battery. 10% on the first ten and 3% on the second. This can not be coincident I agree with Milan.
The real question is what to do?
We can easily proove it if there would be some 3rd party battery out of shimano if that does the same or not. Also would be good to be able to charge such up without the shimano charger. The very best would be to make charging profile at each charging and see how it is changing...
 
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Milan

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Thats all good. I am sure as i wrote something is related to the BMS and please dont get me wrong I am not saying that it is not degrading. I just said feeling point of view not much I recognize.

i tried to make some measurement on that but it is hard in order not woid the warranty.

Never the less it is more than suspicious that 3-4 different riders different usage different kg different charger makes the same output on the battery. 10% on the first ten and 3% on the second. This can not be coincident I agree with Milan.
The real question is what to do?
We can easily proove it if there would be some 3rd party battery out of shimano if that does the same or not. Also would be good to be able to charge such up without the shimano charger. The very best would be to make charging profile at each charging and see how it is changing...
Some say it is the cells, some say it is the BMS, even some other ones say it is a combination of more factors, the actual set up of the bike: anything you may think of, i.e. firmwares, motor, battery. All of that is hard to measure and provide reliable stats as a regular mortal biker :) The only way I can see is an expert who may run a thorough analysis but they would probably need all of our ‘faulty’ set ups to test and this makes things so difficult to arrange. So instead, we will all end up warrantying the batteries until there is a substantial amount of us and Shimano might consider looking into it.
 
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Horse

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Mar 31, 2020
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Hey all

I have a BT-E8035 battery. Also, my battery has lost health very quickly.

My battery stats:

1) # of charging cycles = 10

2) remaining capacity = 90% (dropped to 75% after being plugged in at store for 1st service)

3) charger = EC-E6002

4) km total = 880

5) assistance = most rides 97% eco mode(set at 40%), 1-2% trail, boost almost never, off mode at times riding along the flat, down hills.

6) charging style and storage = bike stored in safe place lol, Battery in my house. Charged prior to biking next day if it requires to be and is ALWAYS charged off the bike in the house. if not biking next day left at what is left (two to three bars).

I have to admit, I use STunlocker to check battery health as I was curious about the the battery state. I bought the bike in September. I have run my battery flat a few times, use the bike 3-4 times a week up until Dec and in all weathers. Had January most of January but was picking up KM's again in Feb until I screwed my leg on a ride!
I took the bike into my local store last week as I hope to start riding soon, battery was around 80% charged. I asked them to do 1st service, check battery health as showing it was dropping 1% every charge and currently showing 90%. I also asked them to check walk assist as it is terrible.
When I got it back they said bike was running latest firmware, battery health was now 75% and in good state. I contacted Shimano and they said to ask the store to warranty the battery as it was obviously faulty. Which I have asked them to do.

I'm really keen to find a better battery to fit as I can see every battery going the same way...800km and battery needs replaced...pretty poor in my opinion.
 
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guika

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Oct 31, 2020
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Hey all

I have a BT-E8035 battery. Also, my battery has lost health very quickly.

My battery stats:

1) # of charging cycles = 10

2) remaining capacity = 90% (dropped to 75% after being plugged in at store for 1st service)

3) charger = EC-E6002

4) km total = 880

5) assistance = most rides 97% eco mode(set at 40%), 1-2% trail, boost almost never, off mode at times riding along the flat, down hills.

6) charging style and storage = bike stored in safe place lol, Battery in my house. Charged prior to biking next day if it requires to be and is ALWAYS charged off the bike in the house. if not biking next day left at what is left (two to three bars).

I have to admit, I use STunlocker to check battery health as I was curious about the the battery state. I bought the bike in September. I have run my battery flat a few times, use the bike 3-4 times a week up until Dec and in all weathers. Had January most of January but was picking up KM's again in Feb until I screwed my leg on a ride!
I took the bike into my local store last week as I hope to start riding soon, battery was around 80% charged. I asked them to do 1st service, check battery health as showing it was dropping 1% every charge and currently showing 90%. I also asked them to check walk assist as it is terrible.
When I got it back they said bike was running latest firmware, battery health was now 75% and in good state. I contacted Shimano and they said to ask the store to warranty the battery as it was obviously faulty. Which I have asked them to do.

I'm really keen to find a better battery to fit as I can see every battery going the same way...800km and battery needs replaced...pretty poor in my opinion.
The only thing you can do , what some folks experienced that , discharge it till it switch off time to time due the BMS does a recalibration. For sure it does not fix the issue ,but there were some reports that % went better after that. So far I did not found any solution for me shimano said that they replace it if it goes under 80%. Also I did not find any 3rd party battery as well… will see. I swallow that and use it, i got a spare one so I can do my rides in any circumstances. I dropped 10kg :) and that increased a lot in range and for strength increase I started to use off mode as well during my trips.
Again i did not find any solution and I wrote down my tips , for sure they are not solutions for the problems. I hope I could help a bit. You are right this is shame on shimano.
 
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Milan

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A little update after sometime...I have just been warrantied my battery. Initial discussions with Shimano started in February. Shimano says that the battery has got an updated firmware. I will check that and post the version later. The old battery, apart from having low capacity around 76%, kept triggering an error of E01030. Since this is a brand new battery and I suppose it is doomed to go through the same fast degrading process would anyone recommend to test/observe/analyze anything to gather evidence? Thanks.
 

guika

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Oct 31, 2020
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A little update after sometime...I have just been warrantied my battery. Initial discussions with Shimano started in February. Shimano says that the battery has got an updated firmware. I will check that and post the version later. The old battery, apart from having low capacity around 76%, kept triggering an error of E01030. Since this is a brand new battery and I suppose it is doomed to go through the same fast degrading process would anyone recommend to test/observe/analyze anything to gather evidence? Thanks.
You mean 8035 has updated battery ? Do you know the version ? So it is not the initial 1.0.0.0 ? How to update that ? Through phone etube ?
 

Milan

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Sep 9, 2020
84
78
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eONEforty - Merida
Hey all

I have a BT-E8035 battery. Also, my battery has lost health very quickly.

My battery stats:

1) # of charging cycles = 10

2) remaining capacity = 90% (dropped to 75% after being plugged in at store for 1st service)

3) charger = EC-E6002

4) km total = 880

5) assistance = most rides 97% eco mode(set at 40%), 1-2% trail, boost almost never, off mode at times riding along the flat, down hills.

6) charging style and storage = bike stored in safe place lol, Battery in my house. Charged prior to biking next day if it requires to be and is ALWAYS charged off the bike in the house. if not biking next day left at what is left (two to three bars).

I have to admit, I use STunlocker to check battery health as I was curious about the the battery state. I bought the bike in September. I have run my battery flat a few times, use the bike 3-4 times a week up until Dec and in all weathers. Had January most of January but was picking up KM's again in Feb until I screwed my leg on a ride!
I took the bike into my local store last week as I hope to start riding soon, battery was around 80% charged. I asked them to do 1st service, check battery health as showing it was dropping 1% every charge and currently showing 90%. I also asked them to check walk assist as it is terrible.
When I got it back they said bike was running latest firmware, battery health was now 75% and in good state. I contacted Shimano and they said to ask the store to warranty the battery as it was obviously faulty. Which I have asked them to do.

I'm really keen to find a better battery to fit as I can see every battery going the same way...800km and battery needs replaced...pretty poor in my opinion.
My assumption is that the cells in these batteries are not faulty. Replacing them will not help. There is something faulty with Shimano BMS or firmware. My original idea was to keep my faulty battery and have the cells replaced but as I was gathering more info I realized that there is a certain trending in degradation and it would not help. It would be great if there is a battery that fits exactly and is not ´produced´ by Shimano. This could resolve the issue.
 

Milan

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You mean 8035 has updated battery ? Do you know the version ? So it is not the initial 1.0.0.0 ? How to update that ? Through phone etube ?
Sure, 8035, I need to check if it is true, I am off for a couple of days but will conect the Shimano diagnostics this week and will let you know the version. I only received it on Friday from Shimano claimng that they have updated the firmware. How? I have no idea.
 
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guika

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Sure, 8035, I need to check if it is true, I am off for a couple of days but will conect the Shimano diagnostics this week and will let you know the version. I only received it on Friday from Shimano claimng that they have updated the firmware. How? I have no idea.
I just checked through phone at the moment and there was nothing. Perhaphs if there is any maybe that requires the service link :/. Waiting for your experience ! Thx Milan!
 

jimbob

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Aug 3, 2020
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A little update after sometime...I have just been warrantied my battery. Initial discussions with Shimano started in February. Shimano says that the battery has got an updated firmware. I will check that and post the version later. The old battery, apart from having low capacity around 76%, kept triggering an error of E01030. Since this is a brand new battery and I suppose it is doomed to go through the same fast degrading process would anyone recommend to test/observe/analyze anything to gather evidence? Thanks.
Interesting. I wonder if they have changed the firmware to just report less degradation, rather than fixing the issue? Maybe I'm too cynical?
 

guika

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Interesting. I wonder if they have changed the firmware to just report less degradation, rather than fixing the issue? Maybe I'm too cynical?
Firmware can help for sure. Look on IOS14.5 changes on battery for iphone 12. Same issue there